Gas turbine engines have been utilized to power a wide variety of vehicles and have found particular application in aircraft. The operation of a gas turbine engine can be summarized in a three step process in which air is compressed in a rotating compressor, heated in a combustion chamber, and expanded through a turbine. The power output of the turbine is utilized to drive the compressor any mechanical load connected to the drive. In general, the construction of these aircraft gas turbine engines involves an axial flow compressor and an axial flow turbine. The turbine is normally divided into a plurality of stages such as, for example, three, and the compressor may be similarly divided into a plurality of stages. Each of the turbine stages is typically coupled to drive a corresponding compressor stage. For example, a high pressure turbine stage is normally coupled in driving relationship to the high pressure compressor stage. In order to achieve this driving function, the turbine stage is coupled through the center portion of the engine to the various compressor stages. Typically, the coupling mechanisms are separate coaxial tubular drive shafts. In other instances, tubular shafts are connected to rotating bores of a turbine disk and interface with mating tubular shafts extending from a bore of a compressor disk in order to define areas of different temperature variations. These latter tubular shafts may be utilized to isolate an area of relatively hot, high pressure gases from relatively cool, lower pressure gases used for downstream cooling air. Since the axial flow of the turbine is generally an annular configuration, tubular joints are necessary to accommodate differential thermal growth over the extent of some tubes.
At each junction in which one tubular shaft interfaces with another tubular shaft, it is known to provide some kind of sealing arrangement between the two shafts. Typically, one of the shafts fits within the other of the shafts and a sealing device such as a piston ring is held in place between the two shafts. This allows relative rotation of one cylinder with respect to the other and at the same time allows axial slippage of the joint. It has been found, however, that in many instances, distortion of the shafts at the joint between the two shafts causes binding such that any differential axial growth may exert axial force on the disks to which the shafts are attached. A substantial axial force may result in interference and possible damage to rotating engine components. Furthermore, such axial growth may result in bending at the slip joint and consequent loss of the seal between the different pressure areas.